DefinitionA pulmonary embolus is a blockage of an artery in the lungs by fat, air, a blood clot, or tumor cells.Alternative NamesVenous thromboembolism; Lung blood clot; Blood clot - lung; Embolus; Tumor embolus; Embolism - pulmonaryCauses, incidence, and risk factorsA pulmonary embolus is most often caused by a blood clot in a vein, especially a vein in the leg or in the pelvis (hip area). The most common cause is a blood clot in one of the deep veins of the thighs. This type of clot is called a deep vein thrombosis(DVT).Less common causes include air bubbles, fat droplets, amniotic fluid, or clumps of parasites or tumor cells, all of which may lead to a pulmonary embolus.Risk factors for a pulmonary embolus include:BurnsCancerChildbirthFamily history of blood clotsFractures of the hips o